1. Field of the Invention
The present invention relates to a termination module for use in an array of modules for terminating transmission lines and in one aspect to a panel for supporting a plurality of modules to be connected to said transmission lines, i.e. optical fibers, copper, aluminum or other conductors, so they can be readily connected to distribution lined leading to opto-electronic or electronic equipment.
2. Description of the Prior Art
The present invention provides a module for connection to the common transmission wires entering a residence or factory or office work station where it is desired to have the service positioned in one spot. This requirement places a plurality of wires in close spaced relationship and it is desirable not to use a lot of space but provide easy access to the transmission lines for connection and disconnection of the distribution cables.
The prior art has a variety of panel configurations for connecting the lines in an incoming cable to the connectors and managing the connection of the lines to distribution lines. Such panels are provided for optical fibers, electrical power distribution, and telephone distribution. The present invention provides a module and panel wherein a plurality of modules can be closely positioned to provide termination of the cables for connection to the cables provided on electronic equipment such as opto-electronic equipment or on electronic equipment such as stereo receivers, television sets, telephones and computer work stations.
The present invention is directed at a simplified array of modules for use in terminating a small number of optical fibers, or fibers and transmission wires such as in an apartment building, a single family residence, or an office or factory work station. The prior art panels in some instances may be modular to afford their use with a small number of fibers but they are adapted to the large termination situations where many fibers or wires are terminated and the panels can be enlarged as the service needed increases. In the present environment it is necessary that the distribution lines be terminated in such a way that they can be connected and disconnected without calling a skilled technician. There are generally only a small number of lines and they should be conveniently packaged to permit a person with minimal assembly skills to make the connections and disconnections to the transmission lines coming into panel. A skilled technician will generally make the connection from the incoming line to the panel connector and then the minimally skilled assembler can make the connection to the panel connector. The connector usually includes a convenient connection to which a plug may then be readily connected to couple the incoming line to the desired equipment.
With optical fiber installations, the technicians are the workers with the responsibility of taking the optical fiber cable that has arrived at the termination station and separating the individual optical fibers from a buffer tube and then splicing them to a fiber end leading from a connector plug. The plugs are subsequently connected to a connector coupling for connection to a plug on a fiber running to an optoelectronic piece of equipment. When this piece of equipment is a piece of equipment in a home, factory or office work station and the number of optical fibers directed thereto are all contained in a single cable, or the cable contains optical fibers together with copper signal wires, it is desirable to have a convenient means of termination of the optical fibers as well as a convenient method of joining the copper wires to a distribution wire. This type of termination should not require any more skill than the technician that would routinely service and install telephone or electrical power. If it requires tools that cut and polish the optical fiber end and special fixtures to secure the finished fiber end in a plug, then the level of skill required to make only several connections at remote locations is economically and commercially disadvantaged, and the optical fiber communication system will not grow and be as readily available to as many citizens as rapidly as desired.
Presently, where large installations are made in a building or central station, a distribution housing is installed and the cable is brought in for distribution. Individual optical fibers from the cable are spliced to long pigtails, each consisting of individually jacketed optical fiber terminated into a connector plug at one end. The pigtail connector plug is mounted into a connector coupling located within the distribution housing or a remote second distribution housing. The splice joining the two fibers is placed within a splice holder within the first distribution housing. The surplus fiber from the pigtail and surplus fiber from the cable are both carefully stored in the distribution housing. A second plug mates with the first in the connector coupling and routes to an optoelectronic device or other intermediate junction. This is the routine which must be followed in the large installations since it is very possible that changes will be needed periodically and access to the splice and the slack fiber will be required. In the home, apartment or factory or office work station on the other hand, the connection will be made and there should be no need for a large distribution panel or box. The termination and its support and the support for the additional slack fiber should not exceed that same requirement for copper communication lines.
A prior device, identified as an optical cable header is described in U.S. Pat. No. 4,585,303. This device utilizes a plurality of optical connector supports which are engaged in a magazine or housing. The connector supports have an elongate body in the form of a hollow finger. The finger has a cylindrical connector member at a front end and a side mounted former upon which to wind a length of fiber located near to its opposite or rear end. The magazine has a row of cavities which are open at the rear of the magazine for receiving the supports and have circular openings in the front wall to receive the connector members on the connector supports when they are received in the cavities. In FIGS. 7-11 the optical connector support is shown to includes a finger, constituted by a rigid metal blade formed of elongate U shape. The optical connector is mounted in the bottom of the U to receive the end fitting of a fiber inside the finger. The optical connector will also receive an analogous end fitting of an external fiber for connection to the fiber inside the finger. The connector described in the introduction is an installed connection end fitting, for example the one described in French patent Nos. 2 275 787 and patent of addition 2 316 611, the earliest patent corresponding generally to U.S. Pat. Nos. 3,989,567 and 4,050,783. This connector is designed to receive one or multiple fibers, but to receive one fiber, requires an installation and in each end fitting, the end face of a fiber is rectified and suitably positioned for providing accurate optical connection when two connection fittings are brought together. The installation of the end fitting is not perceived as a field installation since U.S. Pat. No. 4,585,303 refers to the cable having a plurality of optical fibers with each fiber having a connection end fitting installed on its end. The purpose of the patented header is to avoid having to interrupt the connection of several fibers as with the connector of U.S. Pat. No. 4,050,783, when repairing a defect in the connection between any one pair of fibers. Further, after the supports are placed in the magazine, the connector members on the front face of the magazine are aligned in fixed position in a row and are not readily or individually accessible to make the desired connections.
Another mounting panel with means for supporting a plurality of connectors is shown in U.S. Pat. No. 4,752,110. This patent shows a cabinet for supporting incoming fibers, slack in those fibers, splices, connectors and pigtail fibers, and the plugs for the distribution fibers. This is typical of the prior art and is too bulky and unnecessarily complicated to provide the termination in the residence or apartment building. It is therefore an object of this invention to provide a termination which will reduce the need for large or bulky boxes to handle incoming and connector fibers to afford the installation of optical fibers into a residence and connection of the incoming optical fibers to opto-electronic equipment.
Previous methods of gaining finger access room to tightly spaced connectors have relied on the ability of wire and coaxial cable connections to sustain tight radius curvature and even right angle bends. This ability has allowed designers of connector arrays for electrical conductors to have close clearance in the design of the array through sudden changes in the axis of conductors, and no penalty is incurred by inducing tight bends into the conductors when connections are moved to obtain access.
Electrical connector groupings are also forgiving of movement of jumper wires and connections, since disturbing the connected wires has negligible effect upon signal continuity or transmission.
This is in contrast with optical fiber connections, where the fibers are typically restricted to a bend radius on the order of 20 or more times the outer diameter of the fiber and its jacket. Additionally, movement of optical fiber connections and cables can produce temporary or even permanent loss or reduction in signal carrying ability, due to unintended bending of fibers adjacent to a fiber being connected or removed.
As a result, the schemes which obtain electrical connector access in a tight array, such as through a push-pull action along the axis of the connection, are inappropriate for optical fiber work. The subject action of a slight tilt of the fiber axis is especially apt in that the bend of the fiber which is induced is not only of wide radius, but also the degree of bend is limited to a small arc, and the exiting fiber is subjected to only the minimal translation upwards which will provide access. If translation along the fiber were involved, in most installations, severe problems with bend radius kinks would result along the axis of the fiber. The method in which both of these factors are addressed here can be relied upon to contribute a negligible harm to the transmission properties of the fiber being worked on, and also give a negligible effect to adjacent fibers.
Although these minimal-disruption features are not crucially important in electrical connections, they are nevertheless desirable for connection of coaxial cables and other conductors where cable diameters restrict conductor bending, and in any event comprise a useful and versatile system where it is desired to connect optical fibers and electrical cables in a single housing, or to standardize on a single termination type for a distribution location or system. Frequently, optical fiber cables will also incorporate one or more "talk pairs" or "order pairs" to allow craft persons to communicate during installation or maintenance, or to provide power to run ringing bells, warning lights, and other associated electrical devices on what is primarily an optical transmission system. Hybrid systems with paired wire, coaxial cable and optical fiber for broadband communications are also seen, and a system which can terminate all types of communication media with interchangeable plug-in units has versatility in addition to functional benefits with any one of the media it accommodates.
It is a further object of the present invention to provide a module which can be packaged in an array wherein the modules are in side-by-side relationship to fit in a compact panel, in an array with other modules, in such a manner as to afford ready access to the individual connectors for attachment of the distribution fibers or other lines.